Damage evolution analysis of cast steel GS-20Mn5Vbased on modified GTN model

A modified Gurson-Tvergaard-Needleman(GTN)model that accounts for the mixed(isotropic and kinematic)hardening of cast steel GS-20Mn5V was developed and implemented in the finite element program ABAQUS/Standard via a user-defined material subroutine UMAT. This model couples the stress state and damage evolution(pore volume fraction increase)by a classic method that assumes that the total void volume fraction is divided into a nucleation and a growth part. A parametric study was conducted to assess the effect of modified GTN model parameters on mechanical properties such as the nucleation, growth and coalescence of voids and to obtain the optimal parameter combination by the orthogonal test method. The predicted load-displacement curves of notched specimens with the optimal parameters are favorably compared to the experimental curves. Therefore, the modified GTN model can be used to predict the damage evaluation and fracture behavior of GS-20Mn5V.